Can't use abilities or summoner spells IN GAME!!

every once in awhile when i get in game none of the buttons for my abilities or summoner spells work. It's like the whole keyboard is shut off, however when i press enter those same buttons work when i type in chat. Restarting the game sometimes will resolve this issue, but there have been a few times where it did not so i simply quit the game. This has happened at least 6 times in the last 2 months.